Well pump



July 24, 1956 R. P. VINCENT WELL PUMP 2 Sheets-Sheet l Filed Nov. l0. 1954 FIG. 2

INVENTOR.

T N E C m V P. m N E R ATTORNEY FIG.

July 24, 1956 R. P. VINCENT 2,755,742 I wsu. PUMP Filed Nov. l0. 1954 2 Sheets-Sheet 2 FIG. 3

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ATTORNEY United States Patent() WELL PUMP Renic P. Vincent, Tulsa, Okla., assignor to Stanolind Oil and Gas Company, Tulsa, Okla., a corporation of Delaware Application November 10, 1954, Serial No. 468,033

9 Claims. (Cl. 103-52) This invention relates to an improved well pump. More specifically, this invention relates to a well pump of the type employing cycling free pistons.

Various proposals have been made wherein solid dividers, sometimes referred to as free pistons, swabs or plungers and generally referred to herein as balls, are injected into a well through a power tubing so that well liuids at the bottom of the well are forced ahead and lifted through a production tubing to the surface. The Wellensick Patent 1,932,497 is an example of this type of pump. Various improvements have been made upon that pump, including for example the use of a constriction in the power conduit to reduce the gas/oil ratio by periodically plugging the bottom of the power tubing as disclosed and claimed in my co-pending application S. N. 261,714, now Patent No. 2,698,582. This type of apparatus has, however, received very limited use in deep wells due to the cost of equipping a well with two strings of tubing.

lt is, therefore, an object of this invention to provide an improved well pump. It is a more specific object of this invention to provide a cycling ball well pump which can be installed at a substantially lower initial cost than has been possible heretofore. It is another object of this invention to provide an improved ball injector for a cycling free piston or ball. These and other objects of this invention will become apparent from the following description. In this description reference will be made to the accompanying drawings in which:

Figure l is a view principally in cross-section of a diagrammatic well installation showing an embodiment of my improved well pump;

Figure 2 is a cross-sectional view taken on the line 2 2 of Figure 1;

Figure 3 is a cross-sectional view of an improved ball injector for the well pump shown in Figure l; and

Figure 4 is a view of an alternate well head apparatus.

This invention in brief comprises a cycling free piston pump, often referred to as a ball pump, for a well wherein the balls are circulated in series through the well, the balls being dropped through the annular space within the casing and surrounding the tubing. The balls are caught at the bottom and then lifted to the surface through the production tubing by gas drive whereby the production efficiency of a flowing well or a gas-lift system is materially improved and parailin deposition on the tubing is prevented without substantially increasing the cost of the installation.

Referring-now more specifically to Figure l for a detailed description of this invention, the well is equipped with an external conduit or casing 11 which is .enclosed at the upper end by a tubing head 12. This tubing head has openings for the injector line 13 and a second conduit, the production tubing 14. This tubing extends down through the casing 11 leaving an annular space 1S between the tubing and the casing. As shown in Figure 2,` tubing 14 is held off centerand may be held over "ice against the inside wall of casing 11 by spacer rings 16 which are preferably welded at spaced intervals to the tubing collars 17. The distance between these spacer rings may be varied depending upon the deviation of the well from vertical. In a substantially vertical well, the spacer rings may be placed at a distance of about 500 feet or more but in a typical well having a deviation from vertical of as much as 345 degrees, these rings are generally placed at a distance of about 60-120 feet, preferably about feet. Alternatively the bottom of the tubing may be anchored to the casing or landed on bottom and then by allowing some of the weight ofthe tubing to rest on the bottom support, the tubing tends to spiral in the casing holding the tubing olf center.

Referring now to Figures l and 3, a number of pistons which are typically resilient spheres or balls having a diameter substantially the same as the inside diameter of tubing 14 are inserted in the system by removing the cap 1S on the upper end of tubing 14. The number may be varied at will but as many as two balls are desirably maintained in the system so that one ball can be fallingv while the other ball is being lifted. In the preferred operation where the well fluids are lifted continuously and there are a multiplicity of slugs of liquid flowing through the tubing simultaneously, as many as 25 or more of these balls may be in operation in the system thereby reducing the wear on each ball. The balls injected into the upper end of the tubing are lifted by the well fluids or by gas injected into the casing back through the reverse bend 19 and deposited in a ball injector 20 having a ball hopper 21. These balls 22 fall by gravity or' are forced by the well iluids through the ball hopper until the bottom ball strikes stop 23 which is an exten-V sion of plug 24. This plug is threaded into ball outlet 25 vwhich is coaxial with the ball hopper 21 and is pro# vided in the bottom of injector housing 26 for the purpose of removing balls from the system. The bottom ball in this hopper is thus held in a ball container comprisinga cylindrical opening 27 in injector step piston 28. This cylindrical opening is also coaxial with ball hopper 21 when the step piston is in loading position as shown in Figure 3. The small piston 29 on step piston 28 is sealed in a bushing 30 as by a piston ring (not shown) to isolate the well iluids produced through the tubing from the gas in the injector line 13 and annular space 15. This bushing is ixed in position in the injector housing 26 by a set screw 31. The bushing maybe pressed into the injector housing or otherwise sealed therein as by an O-ring 32. The step piston is adapted to transport the bottom ball within cylindrical opening 2'7 from the bottom of ball housing 21 through bushing 30 into the gas chamber 33 when pressure is applied to the large piston 34 by injecting a high pressure uid such as gas-lift gas into the pressure cylinder 35 through power fluid line 36.

A ball is injected into the annular space 15 each time gas from gas supply line 37 is injected into the well through intermitter valve 38 which may be either pressure or time actuated. This high pressure gas is injected into the annular space through gas line 39 which connects the intermitter valve with the gas chamber33 and then through injector line 13. As gas is injected into the annular space, the pressure in gas chamber 33 and in pressure cylinder 35 is increased. Large piston 34 having a greater cross-sectional area exposed to this pressure than small piston 29, the step piston 28, as shown in Figure 3, is moved to the left transporting the bottom ball in the ball hopper 21 into the gas chamber 33. Gas owing from gas line 39 into the annular space 15 then carries this bottom ball with it down through injector line 13 into this annular space. The axis of cylindrical opening 27 is maintained vertical 4or in alignment with ball hopper 21 by a guide means such as pin 40 fixed to injector housing 26 and extending into a longitudinal groove 41 in step piston 28. The small piston may alternatively be placed eccentrically in the large piston to accomplish the same purpose.

The ball entering the top 'of annular space 15 falls through this space through spacer rings 16 and into a collector such as a funnel 42 which directs the ball via a return bend 43 into Vthe lower end of the; tubing 14. This return bend is preferably located several feet below the producing liquid level 44 in the well. The funnel 42 which may be spaced a short distance, typically lfeet, above the return bend is generally also located below the producing liquid level so that the ball is decelerated by the liquid before the ball strikes the funnel 42. In some cases inlet-ports 45 may be provided at the lower end of the tubing so that the lwell can be pumped'with the liquid level below the top of the funnel 42. Any desired quantity of gas may be admitted to the annular space through intermitter valve 3S. This quantity is determined in accordance with recognized principles of gas lift operation. That is,the amount of gas injected and the pressure built up in annular space 15 is dependent upon the producing characteristics of the well. In a typical intermitter type of operation a ball and a quantity of gas may be injected into the annular space intermittently at time cycles which may vary from a few minutes to several hours or a day or more. The quantity injected on each cycle is desirably only suiiicient to lift a slug of liquid, typically one barrel or less, which is accumulated in the well between injection cycles. This can generally be determined either by calculation or by trial and error as is well known in the art. In some cases, particularly where the well produces with a gas/oil ratio high enough to cause the wellto flow or almost to iiow, only enough gas is injected to actuate the ball injected and inject the ball into the top of the well. Various types of ball injectors can be employed and in some cases mechanically actuated injectors which require no gas injection may be substituted for the gas-actuated ball injector herein specifically described. That is, I have found that by injecting balls into the bottom of the tubing, many Wells which produce with a high gas/oil ratio but which will not produce continuously, the so-called stop-cock gas lift wells, can be. made to produce continually.

Well liquids flowing into a well and accumulating in the bottom are thus periodically lifted in slugs 46 through the tubing either by the gas produced with the well liquid or by the gas injected into the well at the surface. Each of thesel slugs is followed by a piston or ball which seals the tubing, separating the liquid in the slug above the ball from the lifting gas below the ball and preventing slippinge of the gas through the liquid. Slug production in gas lift, as is well known, is desirable for efficient lifting of liquid. Utilizing these cycling balls assures the production of such slugs and since the energy required to drive the ball is substantially negligible, the walls being well lubricated by the well liquid, a high efciency is obtained. After the slug of liquid iiows up through the tubing and reaches the surface, it flows through the perforations 47 into the annular collection chamber 48 to which the ow line 49 is attached. The well liquids ahead and the gas behind the ball are thus displaced through the flow line to storage and the ball separating these two fluids is deposited on top of the other balls in the ball hopper 21.

The step piston is returned to the right or ball loading position after each ball is injected into the annular space by use of a 3-way regulator valve 50. Low pressure gas from the pressure regulator 51 on intermitter valve 38 is applied in parallel under the diaphragms of both the intermitter valve and the 3-way valve to open both valves. As 4the valves are opened, high pressure gas is injected into lthe well, and since bypass valve port 54 is closed when the S-way valve is opened, high pressure gas enters pressure cylinder I through lines 52 and 36. The intermitter yalvean'd 3way valve' are likewise closed and bypass valve `port 54lis opened `simultaneously so that the gas in pressure cylinder 35 is bled oi through the bypass valve port 54 and exhaust port S3 either to the atmosphere or alternately to the flow line 49. As the gas pressure in cylinder 35 is reduced, the pressure in gas chamber 33 drives the step piston back to the right position, as shown in Figure 3, moving the empty cylindrical opening 27 back into axial alignment with ball hopper 21-so that the bottom ball therein is again forced or falls down into the cylindrical opening in position for transfer into the gas stream as described above.

In the preferred embodiment this pump is used to lift well uids continuously rather'th'an intermittently as above described. In this operation gas may be injected through gas line 37 and a choke '61, preferably an adjustable choke, into the injector line 13 and thence into the annular space 15. A bypass line 62 is connected between the gas supply line 37 downstreamfrom-the choke toa controller or intermitter valve 38'. This valve 'is then connected to the ball injector 20' by a line 63. The intermitter valve may be manually or automatically activated to inject balls, preferably at about uniform frequency, into pressure cylinder 35 within the ball injector. This high pressure gas then, acting on the large piston 34' whichin this case is a ilexible diaphragm, due to the difference in areas exposed, moves the step piston 2S' to displace a ball to the left where it'falls into injector line 13 as above described. The injector valve is closed after the step piston has been moved to inject a ball. When the injector valve, which may as above described be a 3-way valve, is closed the pressure on the discharge side is relieved. In one embodiment a small orifice 64 in the bypass line 63, downstream from the intermitter valve, allows the gas in the pressure cylinder 'to lleak to the atmosphere or preferably a small bleed line 65 connectsfthe orifice to the iiow line 49 and allows the high pressure gas in cylinder 35 to escape so that the steppiston is forced, by the pressure of the gas in the annular space-acting on the small piston 29, back to loading position with the opening 27 in axial Valignment with the ball hopper. In one modification of this embodi ment which is particularly useful 'on stop-cock Wells and flowing wells which have paraiiin'problems, the adjustable choke 61 in the gas supply line can be closed and the injector can be actuated using gas produced by the Well. In this embodimentthe operation of the ball injector is identical to the operation using external gas as above described.

As an example of the operation of the invention herein described, an installation of the above-described apparatus was Vmade in Aan 800 foot water well. Ten rubber balls were inserted in the top of the tubing as above described and cycled into the ball hopper. The intermitter valve 38 which was clock operated in this case was set to open at 30`second intervals and to inject about 35 cubic feet of gas at a 'pressure of 165 p. s. i. The well which had a 7- inch casing was equipped with 2inch internal flush tubing having a U bend and funnelfat the bottom which was located at adepth of 745 feet. At a production rate of 400 barrels per' day, each ball lifted a slug of liquid containing about 0114 barrel of water. -The efficiency of lifting -with the ball wasrsubstantially increased las compared to the efficiency of gas lift-without the cyclingfballs. In one comparative test, for example when the injection rate was kept 'constant Vat 62,000 cubic feet per day, the Well without balls produced barrels per day at a gas/liquid ratio of 400 cu.' ft. per barrel and with 1.0 balls cycling in the system it produced 215 barrels per day at a gas/'liquid ratio of 288 cu. ft. per barrel. This increase in lifting efliciency is attributed to the fact that the rubber balls which iit snugly in the tubing permitted no slippage of thegas through he well liquid in the tubing. YDue to thisabsence of slippage, Very short slugs of liquidcould belifted so lthat thepressure of the. gas behind each slug couldvbe reduced substantially as compared to the pressure required Vto lift aflong'slug oflliquid. As a result, the energy in' the gas Wasted after each slug was lifted to the surface was substantially less than in the case where long slugs were lifted as required for efficient operation without the solid dividers or pistons.

From the foregoing description which has been given by way of example, it can be seen that this invention is susceptible of a wide variety of embodiments. For example, while in the above-described embodiment, reference has been made to the injection of gas into the lower end of the production tubing, it will be apparent that gas lift valves could be placed at spaced elevations along the production tubing to assist in kicking the well o and producing the well with the working fluid level substantially above the lower end of the tubing. Thus the above-described apparatus which has all the attributes of an ordinary gas-lift apparatus, has additionally means for cycling solid liquid-gas dividers in the production tubing to improve the lifting efficiency of such ordinary gas-lift apparatus. This invention should therefore not be considered to be limited by the above description but should be construed to be limited only by the scope of the appended claims.

I claim:

l. An apparatus for lifting liquid in a closed vertical conduit comprising a production tubing in said conduit, said conduit and said tubing forming an annular space, means to deliver a series of free pistons into the upper end of said annular space, and means in said annular space at the lower end of said tubing to catch said free pistons and direct them into the lower end of said tubing.

2. In a well pump including an external conduit, an internal conduit, a closed annular space between said external conduit and internal conduit, means to inject a free piston into the upper end of said annular space and means in said annular space at the lower end of said internal conduit to catch said free piston and direct it into the lower end of said internal conduit.

3. A well pump accordidng to claim 2, including means to inject gas into said annular space to gas-lift liquid through said internal conduit.

4. A well pump according to claim 2 including means to inject gas intermittently with said free piston to gaslift liquid through said internal conduit.

5. A well pumping system for lifting liquid comprising a casing, a tubing in said casing, said casing being closed at the top around said tubing to form a closed annular space between said tubing and said casing, a free piston injector for injecting a series of free pistons into the upper end of said annular space, means to inject gas into the upper end of said annular space, means in said annular space at the lower end of said tubing to catch said free pistons and direct them into the lower end of said tubing, means to admit said liquid into the lower end of said tubing, and a free piston separator at the upper end of said tubing, whereby said liquid may flow into the lower end of said tubing and be lifted as a slug through said tubing by said free piston and whereby said free pistons may be separated from said liquids and said gas liquids may be removed from said system to storage.

6. A well pump according to claim 5 wherein said separator returns said free pistons to said free piston injector and discharges said liquid and said gas from said system.

7. In a ball injector for a ball pump having a power conduit for injecting balls into a well, means intermittently to increase the pressure on said power conduit ,a production tubing for lifting well fluids with said balls, a ball separator at the surface to separate balls from said well tluids to discharge said balls into said ball injector and to discharge said well uids from said well, and means to connect said ball injector and said ball separator to said power conduit, the improvement comprising a step piston, a ball holder operatively connected with said step piston, and means to take balls individually in said ball holder from the ball loading position at the ball discharge from said separator to inject each of said balls into said power conduit when the pressure on said power conduit is greater than the pressure on said production tubing at the surface and to return said ball holder to said ball loading position when the pressure on said production tubing is greater than the pressure on said power conduit at the surface.

8. An apparatus to separate a ball from well fluids flowing in a production tubing of a well and inject it into a power conduit of a ball pump comprising a ball hopper connected to the top of said tubing, perforate means in said hopper to separate well lluids from the balls in said hopper, a step piston having a small piston and a large piston, a ball holder in said small piston, a large cylinder for said large piston, a small cylinder for said small piston, said large cylinder and said small piston being substantially longer than said short cylinder whereby said ball holder can be reciprocated from the loading end to the discharge end of said Small cylinder, said large cylinder having one end closed and the other end connected to said loading end of said small cylinder, said small cylinder and said large cylinder being constructed and arranged so that said large piston can reciprocate longitudinally in said large cylinder as said small piston reciproeates through said small cylinder and so that an annular chamber is formed in said large cylinder around said small piston between said large piston and said small cylinder, a ball outlet from said hopper into said annular chamber, said ball holder being aligned With said outlet to receive a ball from said outlet when said step piston is in loading position, a gas line to said well, means connecting said discharge end of said small cylinder to said gas line and means connecting the closed end of said large cylinder to said gas line whereby said hopper discharges a ball into said ball holder when said ball holder is in loading position and when a pressure greater than the tubing pressure is applied to said gas line said step piston is moved to displace said ball holder and the enclosed ball from said loading position to the discharge position, so that the ball can enter said gas line and be carried into said well and whereby said ball holder is displaced back to the loading position when the pressure on said tubing is greater than the pressure on said gas line.

9. An apparatus to separate a ball from well fluids flowing in a production tubing of a well and inject it into a power conduit of a ball pump comprising a ball hopper connected to the top of said tubing, perforate means in said hopper to separate well fluids from the balls in said hopper, a step piston having a small piston and a large piston, a ball holder in said small piston, a small cylinder for said small piston, said small cylinder having a ball loading end and a ball discharge end, means to displace balls from said hopper into said ball holder when said ball holder is in loading position at said ball loading end, means connecting said ball discharge end of said small cylinder to said power conduit for conducting balls from said injector to said power conduit and for applying pressure to the small piston end of said step piston, means to equalize substantially the fluid pressure on opposite ends of said step piston to displace said ball holder from said ball loading end of said small cylinder to said ball discharge end, and means to relieve the pressure on the large piston end of said step piston to displace said small piston and said ball holder back through said small cylinder to said ball loading position.

References Cited in the file of this patent UNITED STATES PATENTS 1,836,874 Picker Dec. 15, 1931 1,932,497 Wellensick Oct. 31, 1933 2,669,936 Elkins et al. Feb. 23, 1954 

1. AN APPARATUS FOR LIFTING LIQUID IN A CLOSED VERTICAL CONDUIT COMPRISING A PRODUCTION TUBING IN SAID CONDUIT, SAID CONDUIT AND SAID TUBING FORMING AN ANNULAR SPACE, MEANS TO DELIVER A SERIES OF FREE PISTONS INTO THE UPPER END OF SAID ANNULAR SPACE, AND MEANS IN SAID ANNULAR SPACE AT THE LOWER END OF SAID TUBING TO CATCH SAID FREE PISTONS AND DIRECT THEM INTO THE LOWER END OF SAID TUBING. 